Apparatus for preparing paper-pulp.



E. D. JEFFERSON.

APPARATUS FOR PREPARING PAPER PULP.

APPLICATION FILED FBB.'7,1912.

I Patented Mar.2,1915. P

3 SHEETS-SHEET l.

E. D. JEFFERSON. APPARATUS FOR PREPARING PAPER PULP.

APPLICATION FILED FEB. 7,1912.

Patented Mar. 2, 1915.

3 SHEETSSHEBT 2. W Q Q;

llll E. D. JEFFERSON. 1 APPARATUS FOR PREPARING PAPER PULP. APPLICATIONFILED FEB. 7,1912.

L1%9,9@40 Patented Mar. 2, 1915.

3 SHEETS-SHEET 3.

the bleaching industry as chemic.

j h ihi APPARATUS FOR PREPARING PAPER-PULP.

Application filed February 7, 1912.

To all whom it may concern Be it known that I, EUGENE D. .InrrnnsoN, acitizen of the United States, residing at Boston, in the county ofSuffolk and State of Massachusetts, have invented certain new andusefulImprovements in Apparatus for Preparing Paper-Pulp; and I do herebydeclare the following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same.

The present invention relatesto apparatus forpreparing paper pulp foruse in paper manufacture. The paper pulp used in the manufacture ofpaper is made from various substances such as wood, rags, jute, grass,etc.

When rags are made into pulp it is necessary to draw or beat the rags,so that they are disintegrated into fiber and no.

longer retain the woven structure of the cloth. In the preparation ofpaper pulp, and particularly pulp made from rags, one of the necessarysteps consists in boiling the material with alkali to soften thematerial, to remove/grease from the material, and to discharge anycoloring matter. To bleach pulp for paper making it is treated with asolution of chlorid of lime which is known in Hitherto it has been thepractice in bleaching paper pulp to beat the pulp in an open hollanderwith the bleaching liquor. A considerable part of the chlorin is lost byevaporation from the open hollander, and the process of bleaching isslow. These two things make the process expensive.

The object of the present invention is to produce an improved apparatusfor preparing pulp for aper making.

with the alibve object in view, one feature of the present inventionrelates to an apparatus for drawing rags preparatory to their use inpaper making.

Another feature of the present invention relates to an apparatuscomprising two tanks in which the pulp is treated with a hot alkalinesolution in the presence of steam, which acts not only to boil thealkaline solution, but also to blow the pulp back and forth between thetwo tanks so that the pulp is thoroughlymixed with the alkali andexposed to the action of live steam.

Another feature of the present invention relates to improved apparatusfor bleaching paper pulp in closed tanks in which the Specification ofLetters Patent.

Patented Mar. 2, rant.

Serial No. 675,965.

apparent to those skilled in the art from the following description.

In the accompanying drawings which illustrate the preferred embodimentof the present invention; Figure 1 is an end elevation of the apparatus;Fig. 2 is a vertical section taken on the line 22 of Fig. 1; Fig. 3 is asectional view of the pilot valve; and Fig. 4 is a sectional view of oneof the diaphragm valves. g

In general, the apparatus consists of two closed gas tight tanks whichare adapted to receive a charge consisting of a mixture of paper pulp orrags and treating liquor and which are placed side by side and connectedby two pipes which extend respectively from the top of either tank tothe bottom of the other tank, and through which the mixture of pulp andtreating liquor is adapted to be blown from the bottom of one tank intothe top of the other tank. The pulp is blown back and forth by means ofcompressed air which is admitted to the tanks alternately by means ofmechanism operated by the rise and fall of the liquor levels in thetanks. Stirrers are employed to still further stir and mix the pulp andtreating liquor and to draw the rags into pulp when rags are to betreated. Each tank is also provided'with a rotatable drum-like strainerfor draining off water during theoperation of washing the treatingliquors from the pulp.

The apparatus will now be described in detail. The two tanks 4 and 6 arehorizontally disposed cylindrical vessels with crowned ends. Two pipes 8and 10 extend from the bottom of the tank 4' to the top of the tank 6and from the bottom of the tank 6 to the top of the tank 4 respectively.The pipes 841ml 10 are "adapted to conduct the mixture of pulp andliquor from the bottom of one tank to the top of the other tank, and

are provided with check valves 12 and 14 respectively to prevent theback flow of air or steam from the top of one tank to the bottom of theother tank. Gate valves 16 and 18 are provided in the pipes 8 and 10.When the material to be treated is rags, the rags in a chopped conditionare put into the tanks through manholes 19. When the charge to betreated consists of pulp' mixed either with water or with alkali or withbleaching liquor, the mixture of paper pulp and liquid is run into thetank through inlets 20 at the top of the tanks, which are provided withgate valves 22. The bleached and washed pulp is drawn off from the tanksthrough pipes 24 provided with gate valves 26.

The motive power for blowing the charge back and forth between the twotanks is either compressed air or steam depending on whether thematerials are to be bleached or boiled. The motive fluid is suppliedthrough a pipe 28 which is provided with a hand valve 30. The pipe 28has two branches 32 and 34 which lead respectively to riser pipes 36 and38 on the tanks 4 and 6. The riser pipes 36 and 38 are continuedupwardly above the connections of the branch pipes 32 and 34 to providevents 40 and 42 for the tanks 4 and 6 respectively. The vents areprovided with hand valves 44 so that they may be restricted as desired.The branch pipes and 34 and the vents and 42 are opened and closed toadmit and exhaust the motive fluid from the tanks by means of diaphragmvalves 46, 48, and 52 respectively, which are operated by the samemotive fluid which is supplied to them through a small pipe 54. Thevalves 46 and 52 are normally closed and are arranged to be opened byfluid pressure in the pipe 54, while the valves 48 and 50 operate in areverse manner, namely, being normally open,

but arranged'to be closed by fluid pressure in the pipe 54. The valves46 and 52 are shown in section in Fig. 4. The valve stem 56 is normallyheld raised by the helical spring 58 to close the valve. The valve isopened by the motive fluid entering the diaphragm chamber 59 through thepipe 54 and pressing down upon a thin metallic diaphragm 60. A plate 62receives pressure from the diaphragm 60 and transmits it to two leverarms 64 which transform a comparatively small downward movement of theplate 62 into a greater movement of the valve stem 56. The valves 48 and50 are similar to the valves 46 and 52 in general construction, but havethe valve and valve seat reversed so that the spring around the valvestem normally holds the valve open and the pressure'on the diaphragmforces down the valve stem to close the valve.

This, of course, necessitates a modification of the valve casing so thatthe valve and valve stem can be inserted from above,

rather than from below as illustrated in Fig. 4. When there is fluidpressure in the pipe 54, the valves 46 and 52 are opened and the valves48 and 50 are closed. The motive fluid is therefore admitted to the tank4, and the motive fluid supply is cut off from the tank 6. The vent ofthe tank 4 is closed, and the vent of the tank 6 is opened so that thecharge which is in the tank4 is blown through the pipe 8 into the top ofthe tank 6. The check valve 14 in the pipe 10, of course, closes underfluid pressure so that the motive fluid cannot pass through the pipe 10.When there is no pressure in the pipe 54, the operation is reversed, thevalves 46 and 52 being closed and the valves 48 and 50 being opened, andthe charge is blown through the pipe 10 from the tank 6 into the tank 4.The motive fluid is admitted to and exhausted from the pipe 54 by meansof a pilot valve indicated generally by reference numeral 61 which iscontrolled by mechanism operated by the rise and fall of the liquorlevels in the tanks. The valve 61 is shown in detail in Fig. 3. Thevalve 61 is placed to supply the small pipe 54 with motive fluid drawnfrom the branch pipe 34 and comprises a coupling 63 in the branch-pipe34 having a laterally projecting nipple 65 which forms the valve casing.The valve proper 68 is arranged to fit against a valve seat 66 to cutoff the flow of mgtive fluid from the pipe 34 to the pipe 54. The valvestem 70 fits loosely in the stem receiving sleeve 71 to provide apassage through which the motive fluid in the pipe 54 is exhausted whenthe valve 68 is seated against the valve seat 66. The valve 68 is alsoarranged to seat against the inner end 73 of the sleeve 71 so that. whenthe valve is open, the leak around the loose valve stem is cut ofl. Thevalve is opened and closed through a link 76 by means of a lever 74which projects upwardly from a rock shaft 78 which is journaled throughgas tight bearings 80 in the tanks. The right-hand end of the rock shaft78, as shown in Fig. 1, has a forwardly projecting arm 82 (see Fig. 2)which carries on its forward end a hollow ball 84. The lefthand end ofthe rock shaft 78 has a rearwardly extending arm 86 which carries ahollow ball 88. When the level of the pulp and liquor mixture in thetank 4 rises to the hollow ball 88, the ball is lifted and the valve 61is opened admitting the motive fluid to the pipe 54, which operates thediaphragm valves 46, 48, 50 and 52 to blow the charge from the tank 4into the tank 6. Similarly, after the charge has been blown into thetank 6, the liquor level rises and lifts the ball 54, closing the valve61 and operating the diaphragm valves, 46, 48, 50 and 52 to blow thecharge back from the tank 6 into the tank 4. Test cocks 120 are providedat iaaaeea the ends of the tanks to indicate the height at which thecontents of the tanks will lift the hollow balls 84 and 88.

Means are provided for stirring the mixture of pulp and treating liquorduring the boiling, bleaching and washing operations and for drawingrags when rags are put into the apparatus. The stirring means comprisestwo worms 90 in each tank. The

them from cloth into a mass of loose fiber.

worms are mounted on hollow shafts 92 and the two worms in each tank arearranged to be rotated in opposite directions. The hollow shafts 92 areprovided with a number of perforations 94 so that water can be admittedto the tanks. The shafts 92 have packed rotary couplings 96 at theoutside of the tank so that the shafts may revolve:

and still receive water. One of the shafts in each tank is driven by aconnection outside of the tank (not shown) and the two shafts are gearedtogether at one end of the tank by gear wheels 98 so that the other wormis driven from the first worm and in an opposite direction to it. Watercan also be admitted into the tops of the tanks 4 and 6 by'means ofwater connections 99. The worm as a stirrer is particularly useful inthe present apparatus since it has no corners to catch and becomeclogged with rags or pulp and at the same time acts very efficiently asa propeller to stir and beat the charge. in this connection it is to benoted that the ends of the worm 90 merge with the shaft 92 with agradual radial taper to avoid corners to catch the materials. Moreover,the provision for forcing water through the perforations 94 afford asure and useful means for loosening any mass of rags or pulp with whichthe worm may become clogged.

A rotary strainer is provided to draw off the treating liquors and thewater used in washing the pulp. The strainer consists of a cylindricalscreen 100 mounted on a hollow shaft 101 which is provided with a numberof perforations 102 and has an outlet 1.04 which may be closed by meansof the gate valve 106. When liquid is being drawn off, the strainer iscontinually rotated to prevent the pulp from clogging the screen so thatthe liquid is more easily drained 011'. During the drawing, boiling andbleaching operations, the strainer is stationary since no liquid isdrawn off. The strainer is rotated by means of a gear 110 which isloosely splined on the forward end of the strainer shaft 101 and isadapted to he slid in and out of engagement with a driving gear 112 onone of the worm shafts 92.

For the sake of fully describing the different operations of which theapparatus is susceptible, the operation will be described first as aseries of operations upon chopped rags including the drawing, boilingand bleaching of the rags to reduce them to.

paper pulp, and then the operation of the apparatus upon pulp which isalready reduced to a fibrous condition will be indicated.

The rags to be treated are introduced into one of the tanks through themanhole 19, and hot water is run in until the tank is partially filledwith water. Then the worms 90 are rotated to beat the rags and drawAfter the rags are beaten for a time, the gear 110 is slid into meshwith the gear 112, and as much of the water as possible is drawn off.Then a solution of alkali is introduced into the tank through the pipe.20 until the liquor level in the tank rises to the height of the testcock 120. Then all of the inlet and discharge valves to the tanks areclosed and live steam'is admitted into the pipe 28 and the valve 30 isopened.

For convenience in description it will be supposed that the rag drawingoperation has taken place in the tank 4 and the alkaline liquor run intothe tank 4. The liquor level at "the test cock 1.20 is sufficient tohave raised the ball 88 so that the valve 61 is open and the steampassesinto the pipe 54, opening the diaphragm valves 46 and 52 andclosing the diaphragm valves 48 and 50. The steam sufliciently to liftthe hollow ball 84 andclose the valve 61, to close the diaphragm valves46 and 52 and open the diaphragm valves 48 and 50, and steam willtherefore be directed into the top of'the tank 6 and blow the chargeback into the tank 4. The operation of blowing the charge from one tankto another is automatically repeated until the rags are thoroughlytreated with the alkali. During the time that the charge is being blownback and forth with the steam the shafts 92 are continuously driven sothat the charge is thoroughly mixed and beaten with the alkali in thepresence of live steam which fills the tanks. The contact of the ragswith the steam materially assists in the action of the alkali inremoving the grease, and particularly in discharging the color since thelive steam acts chemically on the alkali-saturated rags, assisting thechemical reactions and shortening the time necessary for the alkalineboiling.

The extra water caused by the condensation of the steam in boiling thealkaline so- ;lution may be drawn off from time to time through thestrainers 100. After the rag run into this tank through the pipe 99 anddrawn off through the pipe 24, the worms 90 and strainer 100 beingcontinuously rotated. After the alkali is Washed from the pulp, thewater is drawn off and a solution of chlorid of lime or chemic isintroduced through the pipe 20 until the level of the contents of thetank reaches the test cock 120, whereupon the ball 88 is lifted and thepilot valve 60 is opened. The valve 22 is then closed and compressed airunder a pressure of about sixty pounds is admitted to the pipe 28 andthe valve 30 is opened. The compressed air entering the pipe 54 operatesas a motive fluid exactly the same as the steam to actuate the diaphragmvalves 46, 48, '50 and 52, to admit compressed air alternately into thetwo tanks and blow the charge back and forth in bleaching the pulp.During the bleaching operation the valves 44 are partially closed torestrict the vents of the tanks so that when the charge of pulp andbleaching liquor is forced into one tank the air will escape slowly andthe pulp and bleaching liquor will fall through a body of compressed airin the tank. During the time that the charge of pulp and bleachingliquor is .being blown back and forth between the tanks, the worms 90are run to stir the pulp. The pulp is therefore not only exposed to theaction of the air in falling into the tanks from the tops thereof, butis also beaten with the bleaching liquor in the presence of thecompressed air in the tanks. This secures the most advantageous chemicalcondition for bleaching, since to obtain a rapid and complete bleach itis necessary not only to saturate the materials with the chemic, butalso to aerate the materials. In the present apparatus the materials arethoroughly mixed and saturated with chemic and are also aerated withcompressed air. The compressed air is chemically more active in aeratingthe pulp than air at atmospheric pressure, so that the pressure built upby restricting the vents for the tanks accelerates the bleaching. Afterthe pulp is thoroughly bleached the charge is blown into one of thetanks and the air is turned off. Then wash water is run in through thepipe 99 and drawn off through the discharge pipe 24, the gear 110 beingslid into mesh with the gear 112 to rotate the strainer 100 while thewash water is being drawn off from the pulp. After the pulp isthoroughly washed it is drawn off through the discharge pipe 24, airbeing admitted if necessary into the tank to assist in its-discharge.

While the apparatus has been described as being employed to draw, boiland bleach rags, it is equally applicable for operating on pulp such aswood pulp and the like which has already been reduced to disintegratedfiber. When pulp is to be treated,

the manholes 19 are closed and the charge is run in through one of thetanks through the inlet pipe 20 until the level of the charge in thetank reaches the test cock 120. If it is desired to boil the pulp inalkali the alkapipe 28 and the charge is blown back and forth betweenthe tanks until it is bleached. The illustrated apparatus is capable ofcarrying out the three operations of drawing rags into pulp, of boilingthe pulp in alkali, and of bleaching the pulp. However, a simpler formof apparatus which is designed to carry out but a single one of theabove operations or two of them is intended to be within the purview ofthe present invention.

The term pulp as used in the claims is intended to define fibrousmaterial of which paper is made whether in a finished or in a partiallyprepared condition, and therefore is intended to include chopped ragsand similar materials before they are reduced into a condition ofthoroughly disintegrated fiber.

The term liquor as used in the claims is intended to define the variousliquids used in the preparation of'pulp such as the water in whichrags'are drawn, the alkaline bath in which the pulp is boiled, thebleaching liquor, the wash water, etc.

While the present invention is primarily intended to be used in thepreparation of paper pulp, nevertheless it is obvious that it may beused in the preparation of other materials similar to paper pulp, suchas cot-- ton hulls for making cellulose, cotton fiber for making guncotton, etc., and such use is intended to be within the purview of theinvention as defined in the claims.

While the preferred embodiment of the invention has been specificallyillustrated and described, it is to be understood that the presentinvention is not limited to the illustrated embodiment, but may beembodied in other constructions within the scope of the invention asdefined in the following claims:

1. An apparatus for preparing paper pulp having, in combination, twoclosed tanks adapted to receive a charge of pulp and liquor, a pipeconnecting the bottom of the first tank with the second tank having avalve for preventing the flow of motive fluid from the second tank intothe bottom of the first tank, a pipe connecting the bottom of the secondtank with the first tank having a valve for preventing the flow iaaaeea1 of motive fluid from the first tank into the bottom of the secondtank, a motive fluid supply, and means acting automatically to admit themotive fluid into the tops of the tanks alternately for blowing the pulpand bleaching liquor back and forth between the two tanks, substantiallyas described.

2. An apparatus for preparing paper pulp having, in combination, twoclosed tanks adapted to receive a charge of pulp and liquor, means ineach tank for stirring the pulp and liquor, a pipe connecting the bottomof the first tank with the top of the second tank having a valve forpreventing the flow of motive fluid from the second tank into the bottomof the first tank, a pipe connecting the bottom of the second tank withthe top of the first tank having a valve for preventing the flow ofmotive fluid from the first tank into the bottom of the second tank, amotive fluid supply, means acting automatically to admit the motivefluid into the tops of the two tanks alternately for blowing the chargeof pulp and liquor back and forth between the two tanks, substantiallyas described.

3. An apparatus for preparing paper pulp having, in combination, twoclosed tanks adapted to receive a charge of pulp and liquor, a pipeconnecting the bottom of the first tank with the top of the second tankhaving a valve for preventing the flow of motive fluid from the secondtank into the bottom of the first tank, a pipe connecting the bottom ofthe second tank with the top of the first tank having a valve forpreventing the flow of motive fluid from the first tank into the bottomof the second tank, a compressed air supply, means acting automaticallyto admit compressed air into the tops of the two tanks alternately forblowing the charge of pulp and bleaching liquor back and forth betweenthe two tanks, means in each tank for stirring the pulp and liquor, awater supply, means for admitting water to one of the tanks and anoutlet from the same tank provided with strainer for retaining the pulpin the tank so that the pulp may be washed in the tank, substantially asdescribed.

4:. An apparatus for preparing paper pulp, having, in combination, twoclosed tanks adapted to receive a charge of pulp and liquor, a pipeconnecting the bottom of the first tank with the top of the-second tankhaving a valve for preventing the flow of motive fluid from the secondtank into the bottom of the first tank, a pipe connecting the bottom ofthe second tank with the top of the first tank having a valve forpreventing the flow of motive fluid from the first tank into the bottomof the second ,tank, a motive fluid supply, means acting wash wateroutlet for the same tank wash water outlet for the same tank providedwith a strainer for retaining the pulp in the tank during the washingoperation, substantially as described.

5. An apparatus for preparing paper pulp having, in combination, twoclosed tanks adapted to receive a charge of pulp and liquor, a pipeconnecting the bottom of the first tank with the top of the second tankhaving a valve for preventing the flow of motive fluid from the top ofthe second tank to the bottom of the first tank, a pipe connecting thebottom of'the second tank with the top of the first tank having a valvefor preventing the flow of motive fluid from the top of the first tankto the bottom of the second tank, a motive fluid supply, means actingautomatically to admit the motive fluid into the top of the two tanksalternately for blowing the charge of pulp and liquor back and forthbetween the two tanks, means in each tank for stirring the pulpcomprising a rotatably mounted shaft having a worm carried thereon, aWater supply,

means for admitting water to one of the tanks to wash the pulp in thetank and a rovided with a rotatable drum-like strainer for retaining thepulp in the tank during the washing operation, substantially asdescribed.

6. An apparatus for preparing paper pulp having, in combination, twoclosed tanks adapted to receive a charge of pulp and liquor, a pipeconnecting the bottom of the first tank with thetop of the second tankhaving a valve for preventing the flow of motive fluid from the top ofthe second tank to the bottom of the first tank, a pipe connecting thebottom of the second tank with the top of the first tank having a valvefor preventing the flow of motive fluid from the top of the first tankto the bottom of the second tank, a motive fluid supply, means actingautomatically to admit the motive fluid into the tops of the two tanksalternately for blowing the charge of pulp and bleaching liquor back andforth through the pipe connections between the two tanks, a hollow shaftrotatably mounted in one tank having holes through its periphery andhaving a worm carried thereon, means for rotating the shaft to stir thepulp, a water supply, connections for admitting water into the hollowshaiit to wash the pulp in the tank and a wash water outlet for thesametank comprising a rotatable drum-like strainer for retaining the pulp inthe tank during the washing operation, substantially as described.

its

7. An apparatus for preparing paper pulp having, in combination, twoclosed tanks adapted to receive a charge of mixed pulp and liquor, apipe connecting the bottom of the first tank with the second tank havinga valve for preventing the flow of motive fluid from the second tankinto the bottom of the first tank, a pipe connecting the bottom of thesecond tank with the first tank having a valve for preventing the flowof motive fluid from the first tank into the bottom of the second tank,and means aeting automatically to blow the mixture of pulp and liquorback and forth between the tanks comprising a motive fluid supply, abranch pipe from the motive fluid supply to each tank, a vent for eachtank, valves in the branch pipes and vents, and mechanism controlled bythe rise and fall of the liquor levels in the tanks for operating thevalves to admit the motive fluid to one tank, to close the vent of saidtank, to cut off the motive fluid from the other tank and to open thevent of said other tank, substantially as described.

8. An apparatus for preparing paper pulp having, in combination, twoclosed tanks adapted to receive a charge of mixed pulp and liquor, apipe connecting the bottom of the first tank with the second tank havinga valve for preventing the flow of motive fluid from the second tankinto the bottom of the first tank, a pipe connecting the bottom of thesecond tank with the first tank having a valve for preventing the flowof motive fluid from the first tank into the bottom of the second tank,and means acting automatically to blow the mixture of pulp and liquorback and forth between the tanks comprising a motive fluid supply, abranch pipe from the motive fluid supply to each tank, a vent for eachtank, air operated dia phragm valves in the branch pipes and vents, andmechanism for operating said valves to admit the motive fluid to onetank, to close the vent of said tank, to cut off the motive fluid fromthe other tank, and to open the vent of said other tank including a pipeconnection between the motive fluid supply and said diaphragm valves, apilot valve in said connection, and hollow balls in the tanks adapted tobe moved by the rise and fall of the liquor level in the tanks to" openand close the pilot valve, substantially as described.

9. An apparatus for preparing paper pulp having, in combination, a tankfor receiving a charge of pulp and liquor, and means for stirring andwashing the charge comprising a hollow perforated shaft roatablv mountedin the tank, a Worm carried upon said shaft and connections for leadingwater into the hollow shaft, substantially as described.

10. An apparatus for preparing paper pulp having, in combination, aclosed tank adapted to receive a charge of pulp and liquor, and meansfor stirring and washing the pulp comprising a hollow perforated shaftrotatably mounted in the tank, a worm carried by said shaft, connectionsfor lead ing water into the hollow shaft, and-a rotary strainer fordrawing ofl" the liquor from the tank, substantially as described.

11. An apparatus for preparing paper pulp from rags and the like having,in com bination, a tank for receiving a charge of rags and liquor, arotary worm in the tank for drawing the rags to disintegrate them into amass of loose fiber, and means for driving the worm, substantially asdescribed.

12. An apparatus for preparing paper pulp from rags and the like having,in combination, a tank for receiving a charge of rags and liquor, arotary worm located in the tank and near the bottom thereof for drawingthe rags to disintegrate them into a mass of loose fiber and means' fordriving the worm, substantially as described.

18. An apparatus for preparing paper pulp from rags and the like having,in combination, a tank for receiving a charge of rags and liquor, tworotary worms located side by side in the tank and near the bottomthereof for moving the charge in opposite directions and for drawing therags to disintegrate them into a mass of loose fiber, substantially asdescribed. I

14. An apparatus for preparing paper pulp from rags and the like having,in combination, a tank for receiving a charge of rags and liquor, a wormfor drawing the rags to disintegrate them into a mass of loose fiber,the end of said worm being tapered to avoid sharp corners which wouldcatch the rags, and means for driving the worm, substantially asdescribed. a

15. An apparatus for preparing paper pulp from rags and the like having,in combination, a tank for receiving a charge of pulp and liquor, arotary shaft extending into the tank, a Worm wound around the shaft fordrawing the rags to disintegrate them into a mass of loose fiber, theends of said worm merging with the shaft with a gradual radial taper toavoid sharp corners which would catch the rags, and means for drivingthe shaft, substantially as described. EUGENE D. JEFFERSON. Witnesses:

HORACE VAN EVERETT, GEORGE E. S'rEBBINs.

